1 A/1.5 A/2 A Synchronous, Step-Down DC-to-DC Converters Data Sheet ADP2105/ADP2106/ADP2107 FEATURES GENERAL DESCRIPTION Extremely high 97% efficiency The ADP2105/ADP2106/ADP2107 are low quiescent current, Ultralow quiescent current: 20 A synchronous, step-down dc-to-dc converters in a compact 4 mm 1.2 MHz switching frequency 4 mm LFCSP package. At medium to high load currents, these 0.1 A shutdown supply current devices use a current mode, constant frequency pulse-width Maximum load current modulation (PWM) control scheme for excellent stability and ADP2105: 1 A transient response. To ensure the longest battery life in portable ADP2106: 1.5 A applications, the ADP2105/ADP2106/ADP2107 use a pulse ADP2107: 2 A frequency modulation (PFM) control scheme under light load Input voltage: 2.7 V to 5.5 V conditions that reduces switching frequency to save power. Output voltage: 0.8 V to V IN The ADP2105/ADP2106/ADP2107 run from input voltages of Maximum duty cycle: 100% 2.7 V to 5.5 V, allowing single Li+/Li polymer cell, multiple Smoothly transitions into low dropout (LDO) mode alkaline/NiMH cells, PCMCIA, and other standard power sources. Internal synchronous rectifier The output voltage of ADP2105/ADP2106/ADP2107 is adjustable Small 16-lead 4 mm 4 mm LFCSP package from 0.8 V to the input voltage (indicated by ADJ), whereas the Optimized for small ceramic output capacitors ADP2105/ADP2106/ADP2107 are available in preset output Enable/shutdown logic input voltage options of 3.3 V, 1.8 V, 1.5 V, and 1.2 V (indicated by x.x V). Undervoltage lockout Each of these variations is available in three maximum current Soft start levels: 1 A (ADP2105), 1.5 A (ADP2106), and 2 A (ADP2107). Supported by ADIsimPower design tool The power switch and synchronous rectifier are integrated for APPLICATIONS minimal external part count and high efficiency. During logic controlled shutdown, the input is disconnected from the output, Mobile handsets and it draws less than 0.1 A from the input source. Other key PDAs and palmtop computers features include undervoltage lockout to prevent deep battery Telecommunication/networking equipment discharge and programmable soft start to limit inrush current at Set top boxes startup. Audio/video consumer electronics 100 TYPICAL OPERATING CIRCUIT V = 2.5V OUT V = 3.6V IN V = 3.3V IN 0.1F V INPUT VOLTAGE = 2.7V TO 5.5V 10 IN 95 10F FB 90 16 15 14 13 FB GND IN PWIN1 ON OUTPUT VOLTAGE = 2.5V V = 5V IN 1 EN LX2 12 OFF 85 2H 2 GND PGND 11 10F 4.7F ADP2107-ADJ 85k 3 GND LX1 10 80 FB V IN 40k 4 GND PWIN2 9 LOAD 75 COMP SS AGND NC 0A TO 2A 0 200 400 600 800 1000 1200 1400 1600 1800 2000 10F 5 6 7 8 LOAD CURRENT (mA) 1nF 70k Figure 2. Efficiency vs. Load Current for the ADP2107 with V = 2.5 V OUT 120pF NC = NO CONNECT = 2.5 V Figure 1. Circuit Configuration of ADP2107 with VOUT Rev. 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Technical Support www.analog.com 06079-002 EFFICIENCY (%) 06079-001ADP2105/ADP2106/ADP2107 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 External Component Selection ................................................ 17 Applications ....................................................................................... 1 Setting the Output Voltage ........................................................ 17 General Description ......................................................................... 1 Inductor Selection ...................................................................... 18 Typical Operating Circuit ................................................................ 1 Output Capacitor Selection....................................................... 19 Revision History ............................................................................... 3 Input Capacitor Selection .......................................................... 20 Functional Block Diagram .............................................................. 4 Input Filter ................................................................................... 20 Specifications ..................................................................................... 5 Soft Start Period .......................................................................... 20 Absolute Maximum Ratings ............................................................ 7 Loop Compensation .................................................................. 20 Thermal Resistance ...................................................................... 7 Bode Plots .................................................................................... 21 Boundary Condition .................................................................... 7 Load Transient Response .......................................................... 22 ESD Caution .................................................................................. 7 Efficiency Considerations ......................................................... 24 Pin Configuration and Function Descriptions ............................. 8 Thermal Considerations ............................................................ 24 Typical Performance Characteristics ............................................. 9 Design Example .............................................................................. 26 Theory of Operation ...................................................................... 15 External Component Recommendations .................................... 27 Control Scheme .......................................................................... 15 Circuit Board Layout Recommendations ................................... 29 PWM Mode Operation .............................................................. 15 Evaluation Board ............................................................................ 30 PFM Mode Operation ................................................................ 15 Evaluation Board Schematic for ADP2107 (1.8 V) ............... 30 Pulse-Skipping Threshold ......................................................... 15 Recommended PCB Board Layout (Evaluation Board Layout) ......................................................................................... 30 100% Duty Cycle Operation (LDO Mode) ............................. 15 Application Circuits ....................................................................... 32 Slope Compensation .................................................................. 16 Outline Dimensions ....................................................................... 34 Design Features ........................................................................... 16 Ordering Guide .......................................................................... 34 Applications Information .............................................................. 17 Rev. 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